David herbert keeley



(No Model.)

D. H. KEELEY. TELEGRAPH CIRCUIT.

Patented Nov. 11,1890;

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UNITED STATES ATENT DAVID HERBERT KEELEY, OF OTTAWVA, CANADA.

TELEGRAPH-CIRCUIT.

SPECIFICATION forming part of Letters Patent No. 440,164, dated November11, 1890.

Application filed November 4, 1889. Serial No. 329,197. (No model.)

To all whom it may concern.-

Be it known that 1, DAVID HERBERT KEE- LEY, a subject of the Queen ofGreat Britain, residing in Ottawa, in the Province of Ontario, Canada,have invented certain new and useful Improvements i n the Operation ofTelegraph-Circuits, of which the following is a specification.

My invention consists in a new arrangement of signaling apparatuswhereby the interference from statical electricity in a circuit isentirely eliminated.

It has long been recognized that the transmission of signals in atelegraph-circuit is greatly interfered with by the phenomenon of staticcharge and discharge due to the electrification of the conductor, and sowell have the conditions occasioning this phenomenon been studied thatwell-defined laws are laid down in the text-books, whereby the signalingcapacity of any given conductor can be mathematically determined, and ithas be come an accepted fact that the economical operation of a simpleMorse telegraph-line is limited to a certain mileage of the circuitwire.In duplex and other multiplex systems of .telegraphy the practicablelength of line for efficient operation has been limited to a very markeddegree, and in the operation of long submarine cables the speed ofsignaling is far below the practicable rate of an ordinary operatorsmanipulation, despite the use of specially-designed and delicateapparatus.

The object of my invention is to remove the impediment above described,and to render the transmission of signals both in single and duplexcircuits on aerial or submarine wires of the greatestlength easilypracticable at the highest rates of speed. I accomplish this by thesimple expedient of providing a rapidly-reversin g current at thereceiving end of the line, and at the sending end a doublecurrent-transmitter. The receiving-instruments are polarized. If thesending-key is depressed, a current of one polarity (say goes to lineand charges the conductor. If the current-reverser at the distant endpresents a current to line, that current combines with the l currenttransmitted and effects the polarized receiver in one direction, saycloses it. Then the current-reverser presents a current to line, it isopposed by tl1e+current transmitted. Hence no effect is produced in thereceiver, which remains closed. If thekey 5 5 at the sending-station isupraised, a current goes to line. When the current-reverser at thereceiving end presents to line, it combines with the transmitted andeffects the polarized receiverin the direction opposite to that impartedbefore and opens it, and when the current-reverser presents to line itis opposed by the transmitted. Therefore no effect is produced and thereceiver remains open. Hence the distant receiver is actuated 6 5 by thedistant battery under the operation of the sending-key.

The phrase rapidly-reversing current above used does not mean and is notcalculated to imply that the reversals occur more quickly than it wouldbe possible for the armature of the receiving-instrument to follow. Theyare, however, sufficiently rapid to produce and phases twice as fast ascould be produced by a Morse operator 7 5 in n1anipulation-that is tosay, in the formation of a dot on the sending-key a and a current willbe presented to line at the receiving end. On investigation I have foundthat the format-ion of a dot by the operator in Morse transmissions atthe rate of forty words per minute occupies one twentyfourth of asecond. I require, therefore, for the operation of my inventionfortyeight reversals of current per second to accommodate the fastestoperators, while for ordinary rates of transmission lower rates ofreversals will suffice. Since, however, the rate is variable, it wouldbe inexpedient to set down any number invariably. Hence the phrase rap-9o idly-reversing current is employed.

Single Morse circuits of great length have not heretofore beenpracticable, for the reason that in makes and breaks affected bymovements of the key at the sending end the 5 duration of the breaksdoes not allow sufficient time for the charge emanating from the batteryat the distant end to withdraw from the circuit. Thereceiving-instrument consequently remains closed where makes and breaksrapidly occur.

In duplex and other multiplex circuits and in submarine cables thedifficulty is that in many such circuits heretofore thereceivinginstrument is actuated by currents emanating from the sendingend. alone. \Vhen the line is charged and the battery then withdrawn,the charge flows out at both ends to earth at the sending end, andthrough the receiver to earth at the distant end. The discharge-currentrenders the receivers sluggish in action, and the sending-currents mustbe heavy in order to be effectual in the circuits of land-lines operatedin this way. In long cable-circuits heavy currents are inadmissible, aweak current is employed, and it is so attenuated after coursing throughthe great resistance of the conductor that receivinginstruments of greatsensitivencss are necessarily employed. These are therefore renderedcorrespondinglysluggish by the action of the discharge-currents despitethe application of special devices to accelerate their movements, andthe speed attainable in signaling is consequently very low.

From what has heretofore been set forth it will be seen that all of theabove-explained defects are obviated by the device constituting theprincipal element of my invent-ion.

The principle and function of my invention having now been clearly setforth, the method of its application will be readily perceived byreference to the accompanying drawings, in which- Figure 1 shows theplan of equipment of a single circuit. Fig. 2 shows the same withdetails of the current-reverser and receivinginstruments. Fig. 3 showshow my invention is applied to duplex circuits in land lines or cables.

In Fig. 1, at station A, R is a polarized relay of any suitabledescription. Md Mb are main-line batteries connected to the back andfront stops, respectively, of a sendingkey K. The batteries Ma Mb arealso connected to the opposite halves of a two-part commutator O, whichis rotated under the brush Br, and consequently presents to it thecurrents from Ma and Mb alternately. The pole of Ma and the pole of Mbare connected to earth.

S is athree-point switch, to the arm of which the main-line wire,through the relay R, is

connected. When the switch S is closed on the point a, the main line isconnected with the key K, and when S is closed on the point c the mainline is connected with the brush second, or twice as fast as the rate ofpracticable manipulation of a key in Morse transmission. At station Athe key 70 is open and resting on its back stop, and its positionpresents the current of the battery Ma to the main line. The circuit istraced from E at A through battery Ma, key K, point a, switch S, throughrelay R to line, thence through relay R at B, switch S, point 0, wire 4to brush B1" on'the commutator C, thence by wires 5 and Mb to earth at Eor by wire 6' and Ma, to E. There is therefore a current traversing theline from station A. WVhen the commutator C at B presents a current toline, the one neutralizes the other, and no effect is produced in therelays R R but when the commutator O at station B presents a current toline the one current combines with the other, and the combined currentoperates to actuate the relays R R. \Vith the current from A thereforethe current at B operates to actuate the relays, and at B has no effect.As the relays are polarized, the current at B operates to actuate themand move the lever in a certain directionsay to their back stops b b, asshown in the drawings. Now, when the key K at station A is closed andrests on its front stop the current from the battery Mb goes to line.This obviously has the reverse effect of the former current, and currentat station Bis now neutralized, and the current at B operates to actuatethe relays R R in the opposite direction and moves their levers to thefront stops ff. The opening and closing of the key K at station Atherefore causes the relays to be actuated in one direction and theother. Consequently the movements of the key are reproduced by therelays, and signals are transmitted in the usual way.

- In very long lines, or where the discharge or return current due tothe emissions of the batteries at the receiving-stations are veryconsiderable, the connections of the commutator with the batteries aremade at a certain point in each battery, so as not to include the whole,whereas the whole of the battery in each case is included in theconnections with the key. This is shown in the drawings, where the wholeof the battery Mat is connected with the back stop of the key K, and thecommutator O is connected at a certain point in Ma, not including theentire series. The same wit-h respect to the connections of the batteryMb. The object of this arrangement is to make the current transmittedfrom the sending-station paramount in the circuit. When this conditionexists, a given inclination imparted to the relay at the distant stationis maintained despite the contrariwise discharge-current thereoccurring.

In the practical application of the idea involved in the arrangement ofapparatus described in Fig. 1 any suitable means for producing therequisite alterations of current at the receiving end of the circuit maybe applied. Preferably the special device shown in Fig. 2 at station Bisv employed. It consists of a pole-changing transmitter-such as is usedin duplex and quadrnplex systems PC which is operated by theelectro-magnet M, local battery L, and Morse key K in the IIO usual waywhen the switch S is open, and by the automatic circuit-breaker O withits contacts g s when the switch S is closed.

The composition and operation of the automatic circuit-breaker C is asfollows: PM PM are polarized electro-magnets so connected with thebatteries X X that when the lever 71. of PM is against the stop itcloses a circuit, (X wire 11 h 9 PM 5 4 X,) where by the lever h of PMis moved to its top The latter contact closes a circuit, (X 11 10 h 7 PM(3 4 X,) whereby the lever h of PM is moved to its stop and this lattercontact in turn closes a circuit, X 4 5 PM 9 h 8X,) whereby the lei'er hof PM is moved to its stop This latter contact (by the circuit X+4 6 PM7 h 12-X) causes the lever h of PM to again return to its stop-. Theaction is then again repeated and goes on continually. The levers of PMPM are therefore continually oscillated, the rapidity of oscillationbeing determinedby the strength of the batteries X X and the distanceapart of the rest-points of the respective levers. An extension q, witha spring-contact s, can therefore be provided on one of them PM, wherebythe circuit of the pole-changer magnet M may be opened and closedregularly at any desired rate of operation. At station E in Fig. 2 anarrangement of the receivinginstruments is also shown, in which therelay R is associated with an induction-coil I. The primary wire pp ofthe induction-coil is included in the main-line circuit. The relay R isincluded in the circuit of the secondary wire 80, and the friction-jawsgk, moved by the lever Z of the pole-changer PO, operate to close thecircuit of the relay to receive the induced current due to theintroduction of a current into the primary pp, and to open the circuitof the relay before the withdrawal of a current from the primary. Thecircuit of the relay is traced from the secondary so by wire 1, jaw g ork, lever Z, wire 3, relay R, wire 2 to the secondary so. The action ofthe lever l and jaws git is that by friction the jaws remain inwhichever position moved by the lever Z. lVhen Zis drawn down, it leavesg, there by opening the circuit of the relay before the contacty of thepole-changer leaves the spring 4:, which is connected to the pole of thebattery MB, and l closes on the jaw k after the contact g has left 0;and before it touches the spring a, connected with the-pole -of thebattery MB. When the lever l is upraised, the reverse action takesplace. The relay R is in consequence of this device only influenced bythe polarity of the currents introduced into the primary wire pp of theinduction-coil. The object of this is to accelerate the movements of therelay on circuits where extraordinarily rapid transmission of signals isto be effected, in which case a single or phase of thecorrespondingly-rapid reversals of current required at the receiving endof the circuit would be too brief to aifect the relay directly.

Vith the explanation given it will be seen that the arrangements in Fig.2 are substantially the same as in Fig. 1. In Fig. 2 station A isrepresented sending to B. The switch S at A is open. The polechanger PCis operated by the key is. The latter is open and a current is sent toline. Theeircuit is from E at A by wire '0', contact :20, spring a, MBspring 1), contact y, wire w, through relay R to line; thence throughprimary pp of the induction-coil I at station B by wire w, contact 1spring 1;, MB, spring u, contact or, wire 2' to earth at E. The switch Sat station E is closed; but the contacts (13 of the automaticcircuit-breaker O are open. Consequently the lever of the pole-changerPO is unattracted and upraised, and the of the battery MB is presentedto line. A current at station B therefore combines with the current fromstation A, and operates to put the levers of the relays on their backstops b b. A current at station B would neutralize the from A, and therelays would remain undisturbed, while, as before explained, if the keyK at station A were closed and a current transmitted therefrom thecurrent at B, when presented to line, would combine with it and operateto put the relays on their front stops ff. The position of the key atthe sending-station therefore determines the position of the levers ofthe relays, whose actuation, however,

is referable to the allied or opposing forces alternately presented toline at the receiving end of the circuits.

Fig. 3 shows the arrangement of a duplex on the bridge system adaptablewith my improvement to a long land-line or submarine cable-circuit. Thecurrent-alternator, which may be arranged in any suitable way oraccording to that specified in connection with Fig. 2, is represented atC, station A, and is included in a derived circuit from the mainlinewire.

The arrangement and operation of the duplex system beingwell known andunderstood, it will only be sufficient to point out that the existenceof the derived circuit affords two paths for the current sent out toline. One part goes to earth by the derived circuit and the other partthrough the line-wire to earth at the distant station.

According to my arrangement of the apparatus the resistance of thederived circuit is made (by an adjustable resistance X) comparativelylow with reference to that of the line-circuit. Consequently only asmall portion of the current emanating from the sending-battery goes toline. This small current, however, of whatever polarity, is supplementedby a current emanating from a similar derived circuit at the distantend, embracing a current reverser O, and the combined currents operateto actuate the receiving-instruments. There is no synchronism of thecommutators. They are wholly independent. The condition of the circuit(as a whole) is such IIO that very little current from either of thecomm utators passes to line. Their batteries are small compared with thesignaling-batteries. The current from either one of the 'commutatorsoperates to actuate the receiving-instrument at the same end of the linewhere it is located, and the signaling-current, transmitted from adistant end, augments or neutralizes its efiect and controls themovement of the armature of the receivinginstrument. Thesignaling-battery at the same'end of the line as the commutator nowbelng considered has no effect whatever on the, receiving-instrument atthat end, because in the duplex outgoing currents have no effect 1n thereceiver. When the transmitted current is withdrawn from the line,thelatter concurrently discharges by way of the low-resistance circuits inderivation at either end. Consequently there is no lagging effect in thereceiving-instruments, and speedy signaling is accomplished with thegreatest facility.

The operation of the apparatus and circuits is as follows: At station A,R is the polarized receiving instrument or relay included in the neutralwire of the bridge. Rs R90 are the short-arm resistances. X is thebalancingresistance made equal to the joint resistances beyond the point5 of the bridge-connections. Cu is a condenser of small capacity tocompensate for whatever small amount of returncurrent escapes past thederived circuit (5 O.

X E) and passes through the relay. As arranged, it is well understood,the outgoing currents emanating from the battery MB have no effect onthe receiver R, while incoming currents'actuate it. The currentsemanating from the current-reverser G in the derived circuit thereforeflow in, as it were, from the line and affect the relay in one directionand in the other. The joint resistance of the circuits from the point 5to earth being very low compared to the resistance of the main-linecircuit, very little current from G will pass over theline. To producethe proper effect on the relay R, therefore, the currents emanating fromO are not necessarily very strong. Supposing no current is to line atthe distant end, and from O operates to open the relay R, while from Ooperates to close it. If the key at the distant end is closed and sentto line, part of it will pass by way of 5 O X to earth at E, and partthrough the relay R in the same direction as the from C. The relay willtherefore close, and so long as continues to flow from station B therelay R will remain closed, since its presence in R will neutralize theeffect. of the current from C, which would otherwise operate to open it.The reverse effect takes place when is sent from station B. The relay Rat A is therefore actuated by the current from C at A under the controlof the key at the distant end of the circuit. The arrangements beingidentical at both ends of the line, the relay R at B is in like manneroperated by the key at A, theline being thus duplexed.

It is obvious that my improvement may be applied to any other system ofduplex telegraphy in substantially the same wayviz.,by placing acurrent-reverser in derivation to the main line at either end of thecircuit.

Having thus described my invention, I claim 1. In a telegraphic system,a pole-changing transmitter, in combination with a rapidly andconstantly acting current-reverser at the receiving-station for eitherneutralizing or augmenting'the impulses transmitted.

2. In a telegraphic system, a pole-changing transmitter, in combinationwith a receiving apparatus consisting of a polarized relay and a rapidlyand constantly acting current-reverser, whereby the transmitted impulsesare either neutralized or augmented.

3. In a telegraphic system, a main line, including the primary of aninduction-coil,a relay, and a make and break switch included in thesecondary of said coil, in combination with a pole-changer operatingsaid switch to open and close said secondary circuit, and to effect itsclosure before the introduction of a current into and its opening beforethe withdrawal of a current from the said primary, whereby the movementsof the relay on long circuits are accelerated.

4. An automatic circ nit-breaker comprising two polarizedelectro-magnets and two batteries with circuits and contacts and aseparate circuit, all arranged so that the movement of an armature ofone magnet effects a reversal of current in the other magnet, and one ofthe armatures being arranged to make and break the said separatecircuit.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

DAVID HERBERT KEELEY.

\Vitnesses:

F. N. GIsBoRNE, J. S. DAURENT, Jr.

